Investigation of free and impinging jets using generalized k–ω (GEKO) turbulence model

Abstract

The present numerical study focuses on a novel generalized k–ω (GEKO) turbulence model. The model has unique feature of tunable free model parameters C_mix (mixing) and C_jet (jet) applicable for free jets along with C_sep (separation) and C_nw (near wall) used for impinging jets. The slot and circular free jets and impinging jets are employed to assess the model’s consistency in multiple flow aspects. The impinging surfaces are flat plate and cylinder and air is working fluid. Parameters such as velocity, turbulence intensity, turbulence viscosity ratio and Nusselt number are investigated for free and impinging jets. The free parameters have specific range where C_mix = 0.15–0.95, C_jet = 0–1, C_sep = 0.7–2.5 and C_nw = − 2 to 2. The numerical results from C_mix = 0.2 for circular jet, C_mix = 0.3–0.4 for slot jet; C_jet = 0.9 and C_nw = 0.5 for both jet configurations are consistent with existing literature. C_sep = 1.75 for slot jet whereas C_sep = 1–2.5 for circular jet are considered as ideal for numerical prediction. The GEKO turbulence model offers additional feature of production limiter which prevents turbulence increment in stagnation region for impinging jets. Therefore in present study over prediction of numerical heat transfer than experimental is limited to 35 % whereas previous studies have reported it as high as 300 %. Moreover, the GEKO turbulence model is compared with high cost Large Eddy Simulation (LES) which shows excellent numerical competency with LES.